#include <bits/stdc++.h>

using namespace std;

ifstream fin("asmax.in");
ofstream fout("asmax.out");

int n;
int v[16005],dp[16005],grad[16005],radacina;
vector<int>L[16005];

void Citire()
{
    fin>>n;
    for(int i=1;i<=n;i++)
        fin>>v[i];

    for(int i=1;i<=n;i++)
    {
        int x,y;
        fin>>x>>y;
        L[x].push_back(y);
        grad[y]++;
    }

    for(int i=1;i<=n;i++)
        if(!grad[i])
        {
            radacina=i;
            break;
        }
}

void DFS(int nod)
{
    dp[nod]=v[nod];
    for(auto i:L[nod])
    {
        DFS(i);
        if(dp[i]>=0)dp[nod]+=dp[i];
    }
}

void Rezolva()
{
    DFS(radacina);
    fout<<dp[radacina]<<"\n";
}



int main()
{
    Citire();
    Rezolva();
    return 0;
}